Natural Gas is comprised of a mixture of gases (See API 14.1 Section 6.3 and naturalgas.org). Natural gas is bought and sold based on its heating value (BTU) which is derived from a compositional analysis of the natural gas. It is the BTU content that determines the monetary value of a given volume of natural gas. This BTU value is generally expressed in decatherms (one million BTU). In the determination of total heat value of a given volume of gas, a sample of the gas is analyzed and from the composition its heat value per unit volume is calculated. This value is generally expressed in BTU/cu ft. The typical range of transmission quality gas ranges between 1000 and 1100 BTU/cu ft. Production gas, storage facility gas, NGL, and new-found Shale Gas can have much higher heating values up to or even exceeding 1500 BTU/cu ft.
There has been a long-standing controversy between gas producers and gas transporters regarding entrained liquid typically present in most high BTU/cu ft. gas (rich or “wet” gas). Transporter tariffs require essentially liquid-free gas. Liquid in the gas being transported causes operational and safety problems. The practice is to separate the liquid before entering a transport (pipe) line.
The API 14.1 standards (Manual of Petroleum Measurement Standards, 2006) scope does not include supercritical fluid (dense phase) or “wet gas” “(a term referenced by the Natural Gas industry as a gas that is at or below its hydrocarbon dew point temperature and/or contains entrained liquid), nor does the GPA 2166 standard (Obtaining Natural Gas Samples for Analysis by Gas Chromatography, 2005). In summary, there is no known standard which defines how to obtain a “representative sample” of a natural gas supply having entrained hydrocarbon in any form.
Therefore, to fully comply with the current industry standards, membrane-tipped probes such as the A+ Corporation LLC of Gonzales, La., GENIE brand Probe (see assignee U.S. Pat. Nos. 6,357,304, 6,701,794, 6,904,816, 7,004,041, and 7,134,318) have been used for many years to shed entrained liquids inside pressurized pipelines. Other companies such as Valtronics, Inc/Mustang Sampling have bolted enclosures to the A+ Corporation LLC membrane-tipped probes themselves, and power the additional electrically powered heater blocks and cartridge type heated regulators for the enclosure from the electrical heat trace (See Hess U.S. Pat. No. 4,821,905, www.pentairthermal.com, and GB2199451A), and then place A+ Corporation LLC GENIE brand membrane separators (U.S. Pat. No. 7,555,964) in a second enclosure mounted closer to the analyzer (See Mayeaux U.S. Pat. No. 6,357,304, Thompson U.S. Pat. No. 7,162,933, and Thompson US 2012/0325694 A1 as well as Thompson D674,052). Other companies, such as Welker Engineering of Sugar Land Tex., use non-membrane probes and bring the liquids outside the pipeline to reject them, hanging a hinged enclosure onto the probe (see Welker SCHS data sheet). Welker and other companies such as PGI install sample pumps and composite samplers and bolt enclosures to the pipeline (see Welker U.S. Pat. No. 5,531,130 and Nimberger U.S. Pat. No. 5,109,709).
Each of these enclosure systems are engineered for one specific configuration, and once the probe housing or pump is installed, it cannot be removed without shutting down and depressurizing the process.
In Thompson U.S. Pat. No. 7,162,933, an enclosure is provided with a Mayeaux U.S. Pat. No. 6,357,304 type probe, provided by A+ Corporation LLC of Gonzales, La., and diagonal enclosure such as Hess U.S. Pat. No. 4,821,905 along with a heat trace splice kit such as Raychem S150-ML and Tyco Electronics Raychem GB 2199451A.
Welker has a similar, two half-horizontal enclosure in U.S. Pat. No. 5,531,130 as does Hess U.S. Pat. No. 5,581,033A.
The Welker SCHS brochure depicts a vertical version of the two-half enclosure with a hinged door. Nimberger U.S. Pat. No. 5,109,709 utilizes a hinged door as well. Thompson US2012/0325694 A1 attempts to increase access to the probe inside the enclosure from using one like Hess U.S. Pat. No. 5,581,033A by using a diagonal-half approach like Hess U.S. Pat. No. 4,821,905. While this change may increase accessibility by 20%-30%, it still leaves much to be desired for component access. Further, the pipeline must be shut down and depressurized to install and remove the probe with all prior art.
All the existing art relies on power being readily available for electrical heater devices and electrical heater blocks to provide heat for the sample systems.
Many of the sample points where the sample installations are present are in small diameter pipelines with limited electrical power available or only low wattage close proximity solar power available. Solar power has been traditionally used in natural gas sampling for decades. See U.S. Pat. No. 5,501,080A, McManus et al, with 1994 Priority date as well as vendors such as ABB, web site www.new.abb.com/solar which pre-dates Thompson U.S. Pat. Nos. 9,459,185 and 9,733,224. Also see Mayeaux U.S. Pat. No. 7,051,604 wherein the second embodiment teaches the use of vacuum jacketed means for a fluid sample system from a pipeline. Some of the sample points will only have solar power available for the short distance of self-limited heat trace tubing.